纹理不应用于生成的网格

有一个问题，一个脚本，其中一个简单的景观是从三角形生成的。并且草的纹理是通过脚本叠加的。但是在应用纹理之后，网格变成了绿色，好像从纹理中取出了 1 个像素。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[RequireComponent(typeof(MeshFilter))]
public class ProceduralTerrain : MonoBehaviour
{
Mesh mesh;

Vector3[] vertices;
int[] triangles;

public Renderer rend;
public Texture[] textures;

public int xSize = 100;
public int zSize = 100;

private void Start()
{
    mesh = new Mesh();
    GetComponent<MeshFilter>().mesh = mesh;
    rend = GetComponent<Renderer>();


    rend.material.mainTexture = textures[0];

    CreateShape();
}

private void Update()
{
    UpdateMesh();
}

void CreateShape()
{
    vertices = new Vector3[(xSize + 1) * (zSize + 1)];  //Getting size of grid

    for(int i = 0, z = 0; z <= zSize; z++)
    {
        for (int x = 0; x <= xSize; x++)
        {
            //Setting PerlinNoise and calculating grid
            float y = Mathf.PerlinNoise(x * .01f, z * .01f) * 50f;
            vertices[i] = new Vector3(x, y, z);
            i++;
        }
    }

    triangles = new int[xSize * zSize * 6];


    //setting triangles and verts for simple quad
    int vert = 0;
    int tris = 0;
    for (int z = 0; z < xSize; z++)
    {
        for (int x = 0; x < xSize; x++)
        {

            triangles[tris + 0] = vert + 0;
            triangles[tris + 1] = vert + xSize + 1;
            triangles[tris + 2] = vert + 1;
            triangles[tris + 3] = vert + 1;
            triangles[tris + 4] = vert + xSize + 1;
            triangles[tris + 5] = vert + xSize + 2;

            vert++;
            tris += 6;

        }
        vert++;
    }
}

void UpdateMesh()
{
    mesh.Clear();

    mesh.vertices = vertices;
    mesh.triangles = triangles;
    mesh.RecalculateNormals();
}

}

谢谢你。